| 摘要 |
987,702. Springs. SANDVIKENS JERNVERKS A.B. Feb. 13, 1962 [July 21, 1961], No. 5482/62. Heading F2S. [Also in Division G3] In a coil spring of the spiral type, designed e.g. as a main spring for a watch or clock, low friction between adjacent surfaces of the coils of the spring when wound is achieved by coating at least a part of one of the surfaces with a layer of polymerized tetrafluoroethylene or similar polymer or copolymer in which a small proportion of the fluorine atoms have been replaced by other atoms or groups the thickness of which, along the main part of the width of the layer, is 2 to 15 microns. The coating may be in the form of a filament which is bonded to the spring by sintering before coiling and which forms a layer of preferably between one tenth and half of the width of the spring. The coating layer, which may have a thickness of from one to ten per cent of the thickness of the spring, can be applied in the form of an aqueous dispersion with surface and wetting agents added the grains of the dispersion being sintered together by baking before the coiling operation of the spring. The subsequent tempering of the spring within the temperature range of 350‹-500‹ C. is stated not to affect adversely the properties of the coating. In a modification, Fig. 3, not shown, the layers 5, 6 have a convex outer surface. In a further modification the spring has a slightly curved cross-section. |
